Horses can detect fear in humans by smell, becoming more likely to startle and more wary of people who are scared

A new study published in the journal PLOS One finds that horses can detect fear in humans by smell, becoming more likely to startle and more wary of people who are scared. Researchers collected odor samples from the armpits of human study participants and observed the horses' behavior when exposed to these odors. The study suggests that horses can smell how we feel, even if they can't hear or see us, providing evidence of cross-species 'emotional contagion'.